1. Field of the Invention
A toroidal type continuously variable transmission according to the present invention is used, for example, as a speed change unit of a transmission of a motor vehicle or transmissions of various industrial machines, respectively.
2. Related Background Art
It has been investigated that a toroidal type continuously variable transmission schematically shown in FIGS. 24 and 25 is used as a transmission of a motor vehicle. For example, as disclosed in Japanese Utility Model Laid-Open No. 62-71465 (1987), in such a toroidal type continuously variable transmission, an input disc 2 is supported in coaxial with an input shaft 1 and an output disc 4 is secured to an end of an output shaft 3 disposed in coaxial with the input shaft 1. Within a casing (described later in connection with FIGS. 26 to 28) containing the toroidal type continuously variable transmission, there are provided trunnions 7 rockable around pivot shafts 6.located at positions twisted with respect to the input shaft 1 and the output shaft 3.
That is to say, each trunnion 7 is provided at its both end outer surfaces with the pivot shafts 6 in coaxial with each other. Accordingly, the pivot shafts 6 do not intersect with center lines of the discs 2, 4 but extend in perpendicular to such center lines. Further, central portions of the trunnions 7 support proximal ends of displacement shafts 8 so that inclination angles of the displacement shafts 8 can be adjusted by rocking or swinging the trunnions 7 around the pivot shafts 6. Power rollers 9 are rotatably supported around the displacement shafts 8 supported by the trunnions 7. The power rollers 9 are interposed between the input disc 2 and the output disc 4. Inner surfaces 2a, 4a of the discs 2, 4 which are opposed to each other have concave surfaces obtained by rotating arcs having centers on the pivot shaft 6 around the input shaft 1 and the output shaft 3. Peripheral surfaces 9a of the power rollers 9 having spherical convex shapes abut against the inner surfaces 2a, 4a. A pressing device 10 of loading cam type is disposed between the input disc 2 and the output disc 4 so that the input disc 2 is can be urged elastically toward the output disc 4 by the pressing device 10. The pressing device 10 comprises a cam plate 11 rotated together with the input shaft 1, and a plurality (for example, four) of rollers 13 held by a holder 12. One side surface (left side surface in FIGS. 24 and 25) of the cam plate 11 is constituted as a cam surface 14 having unevenness or undulation extending along a circumferential direction, and an outer surface (right side surface in FIGS. 24 and 25) of the input disc 2 has a similar cam surface 15. The plurality of rollers 13 are rotatably supported for rotation around axes extending radially with respect to the center line of the input shaft 1.
In use of the toroidal type continuously variable transmission having the above-mentioned construction, when the cam plate 11 is rotated as the input shaft 1 is rotated, the plurality of rollers 13 are urged against the cam surface 15 formed on the outer surface of the input disc 2 by the cam surface 14. As a result, the input disc 2 is urged against the plurality of power rollers 9, and, at the same time, due to the frictional engagement between the pair of cam surfaces 14, 15 and the plurality of rollers 13, the input disc 2 is rotated. Rotation of the input disc 2 is transmitted to the output disc 4 through the plurality of power rollers 9, thereby rotating the output shaft 3 secured to the output disc 4.
In a case where a rotational speed ratio (speed change ratio) between the input shaft 1 and the output shaft 3, when deceleration is effected between the input shaft 1 and the output shaft 3, the trunnions 7 are rocked or swung around the pivot shafts 6 in predetermined directions, thereby including the displacement shafts 8 so that the peripheral surfaces 9a of the power rollers 9 abut against a portion of the inner surface 2a of the input disc 2 near the center and a portion of the inner surface 4a of the output disc 4 near its outer periphery, respectively, as shown in FIG. 24. On the other hand, when acceleration is effected, the trunnions 7 are rocked around the pivot shafts 6 in opposite directions, thereby inclining the displacement shafts 8 so that the peripheral surfaces 9a of the power rollers 9 abut against a portion of the inner surface 2a of the input disc 2 near its outer periphery and a portion of the inner surface 4a of the output disc 4 near the center, respectively, as shown in FIG. 25. If the inclination angles of the displacement shafts 8 are selected to an intermediate value between FIG. 24 and FIG. 25, an intermediate speed change ratio can be obtained.
When the actual transmission of the motor vehicle is constituted by the above-mentioned the toroidal type continuously variable transmission, it is well known in the art to provide a so-called toroidal type continuously variable transmission of double cavity type in which two sets of input disc 2, output disc 4 and power rollers 9 are prepared, and such two sets of input disc 2, output disc 4 and power rollers 9 are arranged in parallel to each other along a power transmitting direction. FIGS. 26 and 27 show an example of such a toroidal type continuously variable transmission of double cavity type disclosed in Japanese Patent Publication No. 8-23386 (1996).
An input shaft la is supported within a casing 5 for only rotation. A cylindrical transmission shaft 16 is rotatably supported around the input shaft 1a in coaxial with the latter for rotation relative to the input shaft 1a. First and second input discs 17, 18 corresponding to first and second outer discs of the present invention are supported on both ends of the transmission shaft 16 via ball splines 19 so that inner faces 2a of these discs are opposed to each other. Accordingly, the first and second input discs 17, 18 are rotatably supported within the casing 5 in coaxial with and in synchronous with each other.
Further, first and second output discs 20, 21 corresponding to first and second inner discs of the present invention are supported around an intermediate portion of the transmission shaft 16 via a sleeve 22. An output gear 23 is integrally formed on an outer peripheral surface of an intermediate portion of the sleeve 22, and the sleeve has an inner diameter greater than an outer diameter of the transmission shaft 16. The sleeve is rotatably supported by a support wall 24 provided within the casing 5 via a pair of bearings 25 in such a manner than the sleeve is disposed in coaxial with the transmission shaft 16 and can merely be rotated. In this way, the first and second output discs 20, 21 are spline-connected to both end of the sleeve 22 rotatably mounted around the intermediate portion of the transmission shaft 16 in a condition that inner surfaces 4a of the discs 20, 21 are directed toward opposite directions. Accordingly, the first and second output discs 20, 21 are supported in coaxial with the first and second input discs 17, 18 and are rotated independently from the first and second input discs 17, 18 in a condition that the inner surfaces 4a are opposed to the respective inner surfaces 2a of the first and second input discs 17, 18.
Further, two pair of yokes 26a, 26b are supported by an inner wall of the casing 5 at both sides of the first and second output discs 20, 21 with the interposition of these output discs 20, 21. The yokes 26a, 26b correspond to yokes constituting first and second supporting means of the present invention and are formed as rectangular frames, respectively, by press-working a metal plate such as a steel or forging metal material such as steel. The yokes 26a, 26b are provided at their four corners with circular support holes 31 for rockably supporting first and second pivot shafts 29, 30 provided on both ends of first and second trunnions 27, 28 (described later) and are also provided with circular locking holes 32 formed in central portions of the yokes in a width-wise direction (left-and-right direction in FIGS. 27 and 28) thereof at both ends of the transmission shaft 16 in an axial direction (left-and-right direction in FIG. 26) thereof. The pairs of yokes 26a, 26b each having the above-mentioned configuration are supported by support ports 33a, 33b formed on opposed portions of the inner wall of the casing 5 for slight displacement. The support posts 33a, 33b are opposed to each other and are disposed within a first cavity 34 between the inner surface 2a of the first input disc 17 and the inner surface 4a of the first output disc 20 and a second cavity 35 between the inner surface 2a of the second input disc 18 and the inner surface 4a of the second output disc 21. Accordingly, in a condition that the yokes 26a, 26b are supported by the support posts 33a, 33b, one ends of the yokes 26a, 26b are opposed to an outer peripheral portion of the first cavity 34 and the other ends are opposed to an outer peripheral portion of the second cavity 35.
Further, a pair of first trunnions 27 are disposed within the first cavity 34 at diametrically opposed positions of the first input disc 17 and the first output disc 20, and a pair of second trunnions 28 are disposed within the second cavity 35 at diametrically opposed positions of the second input disc 18 and the second output disc 21. As shown in FIG. 27, the four (in total) first pivot shafts 29 which are coaxially provided on both ends of the trunnions 27 (two in each trunnion) are supported by one ends of the pair of yokes 26a, 26b for rocking movement and axial displacement. That is to say, the first pivot shafts 29 are supported within the support holes 31 formed in one ends of the yokes 26a, 26b via radial needle bearings 36. Each of the radial needle bearings 36 has an outer race 37 having a spherical convex outer peripheral surface and a cylindrical inner peripheral surface, and a plurality of needles 38. Accordingly, the first pivot shafts 29 are supported at both axial sides on one ends of the yokes 26a, 26b for reversible rocking movement and axial displacement. Further, as shown in FIG. 28, the four (in total) second pivot shafts 30 which are coaxially provided on both ends of the second trunnions 28 (pair in each trunnion) are supported within the second cavity 35 in the same manner as the first pivot shafts 29 provided on the first trunnions 27.
The first and second trunnions 27, 28 supported within the casing 5 for rocking movements and displacements in axial directions of first and second pivot shafts 29, 30 in this way are provided at their intermediate portions with circular holes 39, as shown in FIGS. 27 and 28. The first and second displacement shafts 40, 41 are supported in these circular holes 39. The first and second displacement shafts 40, 41 have support shaft portions 42 parallel with and eccentric with each other, and pivot shaft portions 43. The support shaft portions 42 are rotatably supported within the circular holes 39 via radial needle bearings 44. Further, first and second power rollers 45, 46 are rotatably supported around the pivot shaft portions 43 via other radial needle bearings 47.
Incidentally, the pair of first and second displacement shafts 40, 41 provided for each of the first and second cavities 34, 35 are disposed at opposite directions (diametrically opposed at 180 degrees) with respect to the input shaft 1a and the transmission shaft 16 for each of the first and second cavities 34, 35. Further, directions along which the pivot shaft portions 43 of the first and second displacement shafts 40, 41 are offset (eccentric) from the support shaft portions 42 are the same (up-and-down opposite directions in FIGS. 27 and 28) with respect to the rotational direction of the first and second input and output discs 17, 18, 20, 21. Further, the eccentric directions are substantially perpendicular to an installation direction of the input shaft 1a. Accordingly, the first and second power rollers 45, 46 are supported for slight displacement in the installation direction of the input shaft 1a and the transmission shaft 16 (slight axial displacement). As a result, if the first and second power rollers 45, 46 tend to be displaced in the axial direction of the input shaft 1a and the transmission shaft 16 (left-and-right direction in FIG. 26, and, direction perpendicular to the planes of FIGS. 27 and 28) by change in elastic deformation amount of constructural parts due to fluctuation in torque to be transmitted by the toroidal type continuously variable transmission, such displacement can be absorbed without acting any excessive stress on the constructural parts.
Further, between outer surfaces of the first and second power rollers 45, 46 and inner surfaces of intermediate portions of the first and second trunnions 27, 28, there are provided, in order from the outer surfaces of the first and second power rollers 45, 46, thrust ball bearings 48, and thrust bearings 49 such as sliding bearings or needle bearings. The thrust ball bearings 48 serve to support thrust load acting on the first and second power rollers 45, 46 and to allow rotations of the first and second power rollers 45, 46. Further, the thrust bearings 49 serve to support thrust loads acting on outer races 50 of the thrust ball bearings 48 and to allow the pivot shaft portions 43 and the outer races 50 to rock around the support shaft portions 42.
Further, drive rods 51 are connected to one ends (lower ends n FIGS. 27 and 28) of the first and second trunnions 27, 28, and drive pistons 52 are secured to outer surfaces of intermediate portions of the drive rods 51. The drive pistons 52 are slidably mounted within drive cylinders 53 in an oil-tight fashion. The drive pistons 52 and the drive cylinders 53 constitute actuators for displacing the first and second trunnions 27, 28 along the axial directions of the first and second pivot shafts 29, 30. Further, pressurized oil can be supplied within the drive cylinders 53 in response to switching of a control valve (not shown).
Further, an pressing device 10 of loading cam type is disposed between the input shaft 1a and the first input disc 17. The pressing device 10 includes a cam plate 11 spline-connected to the intermediate portion of the input shaft 1a so that it can be rotated together with the input shaft 1a but cannot be displaced in the axial direction, and a plurality of rollers 13 rotatably held by a holder 12. When the input shaft 1a is rotated, the pressing device serves to rotate the first input disc 17 while urging it toward the second input disc 18.
When the toroidal type continuously variable transmission having the above-mentioned construction is driven, the rotation of the input shaft 1a is transmitted to the first input disc 17 through the pressing device 10, so that the first and second input discs 17, 18 are rotated in synchronous with each other. The rotation of the first and second input discs 17, 18 is transmitted to the first and second output discs 20, 21 through the pairs of first and second power rollers 45, 46 disposed within the first and second cavities 34, 35. The rotation of the first and second output discs 20, 21 is picked-up by the output gear 23. When the rotational speed ratio between the input shaft 1a and the output gear 23 is changed, by switching the control valve, the pairs of drive pistons 52 corresponding to the first and second cavities 34, 35 are displaced in opposite directions by the same distance for the cavities 34, 35, respectively.
When the drive pistons 52 are displaced, two pairs (four in total) of trunnions 27, 28 are displaced in opposite directions, so that, for example, the first and second power rollers 45, 46 at the right in FIGS. 27 and 28 are shifted downwardly (FIGS. 27 and 28) and the first and second power rollers 45, 46 at the left in FIGS. 27 and 28 are shifted upwardly (FIGS. 27 and 28). As a result, directions of tangential forces acting on the contact areas between the peripheral surfaces 9a of the first and second power rollers 45, 46 and the inner surfaces 2a, 4a of the first and second input discs 17, 18 and the first and second output discs 20, 21 are changed. As the directions of forces are changed, the first and second trunnions 27, 28 are rocked in opposite directions around the first and second pivot shafts 29, 30 supported by the yokes 26a, 26b. As a result, as shown in FIGS. 24 and 25, the contact areas between the peripheral surfaces 9a of the first and second power rollers 45, 46 and the inner surfaces 2a, 4a of the discs 17, 18, 20, 21 are changed, thereby changing the rotational speed ratio between the input shaft 1a and the output gear 23.
By the way, in the conventional arrangement shown in FIGS. 26 to 28, the first and second trunnions 27, 28 are supported within the casing through the support posts 33a, 33b and the yokes 26a, 26b. Thus, since the number of parts is increased, not only manufacture, control and assembling of the parts become troublesome, but also height of the toroidal type continuously variable transmission in the up-and-down direction in FIGS. 26 to 28 is increased, so that it is hard to make the transmission compact and light-weighted. Further, if the transmission is forcibly made compact and light-weighted to permit installation of the transmission within a limited space, strength of parts is decreased, thereby worsening endurance.
Japanese Patent Laid-Open No. 10-274300 (1998) discloses an arrangement in which pivot shafts provided on both ends of trunnions constituting a toroidal type continuously variable transmission are supported by support members directly secured to an inner surface of a casing. With this arrangement, since the number of parts is decreased, the transmission can be made compact and light-weighted. However, in case of the toroidal type continuously variable transmission disclosed in this document, the support members for supporting the pivot shafts provided on both ends of the trunnions are independently provided for each trunnion.
Thus, in the arrangement disclosed in the above Japanese Patent Laid-Open No. 10-274300, loads acting on the trunnions when the toroidal type continuously variable transmission is driven directly act on the casing. That is to say, when the toroidal type continuously variable transmission is driven, since pressure acting on contact areas between inner surfaces of input and output discs and peripheral surfaces of power rollers is great, the power rollers are subjected to great thrust loads. Such thrust loads act on the support portions for the pivot shafts provided on both ends of the trunnions through the trunnions. In the arrangement disclosed in above-mentioned document, the great loads acting on the pivot shafts in this way act on the casing as they are. In many cases, since the casing of the transmission is made of light alloy such as aluminium alloy to reduce the weight, in order to prevent displacement of the pivot shafts and to ensure the endurance of the casing regardless of great loads, it is necessary to increase a wall thickness of the casing, with the result that it is hard to make the transmission compact and light-weighted.
Further, when the toroidal type continuously variable transmission is driven, due to the great loads acting on the trunnions from the power rollers, the trunnions are elastically deformed so that the inner surfaces thereof becomes concave. As a result, parallelism between central axes of the pivot shafts provided on the ends of the trunnions and central axes of circular holes formed in the support members secured to the inner surface of the casing is lost more or less. In the arrangement disclosed in above-mentioned document, it is not considered that the trunnions can be displaced smoothly without damaging any parts even if such a condition occurs.
In consideration of the above circumstances, a toroidal type continuously variable transmission according to the present invention is devised.
As is in conventional toroidal type continuously variable transmissions, a toroidal type continuously variable transmission according to the present invention comprises a casing, input and output discs supported within the casing in coaxial with each other and capable of being rotated independently, the even number of pivot shafts disposed in coaxial with or parallel with each other between the discs at twisted positions where the pivot shafts do not intersect with a central axis of the discs but extend toward directions perpendicular to the central axis, a plurality of trunnions rockable around the pivot shafts, displacement shafts protruded from inner surfaces of the trunnions, a plurality of power rollers rotatably supported around the displacement shafts and interposed between inner surfaces of the input and output discs, and support means provided at sides of the power roller and adapted to support the pivot shafts for rocking displacement and axial displacement.
Further, as is in conventional toroidal type continuously variable transmissions, a toroidal type continuously variable transmission according to the present invention comprises a casing, first and second outer discs supported within the casing in coaxial with each other and capable of being rotated synchronously so that inner surfaces of the discs are opposed to each other, a first inner disc supported in coaxial with the first and second outer discs and capable of being rotated independently from the first and second outer discs and having an inner surface opposed to the inner surface of the first outer disc, a second inner disc supported in coaxial with the first inner disc and capable of being rotated synchronously with the first inner disc and having an inner surface opposed to the inner surface of the second outer disc, four first pivot shafts disposed in coaxial with or parallel with each other between the first outer disc and the first inner disc at twisted positions where the pivot shafts do not intersect with a central axis of these discs but extend toward directions perpendicular to the central axis, a pair of first trunnions rockable around the first pivot shafts, first displacement shafts protruded from inner surfaces of the first trunnions, a pair of first power rollers rotatably supported around the first displacement shafts and interposed between the inner surface of the first outer disc and the inner surface of the first inner disc, four second pivot shafts disposed in coaxial with or parallel with each other between the second outer disc and the second inner disc at twisted positions where the pivot shafts do not intersect with a central axis of these discs but extend toward directions perpendicular to the central axis, a pair of second trunnions rockable around the second pivot shafts, second displacement shafts protruded from inner surfaces of the second trunnions, a pair of second power rollers rotatably supported around the second displacement shafts and interposed between the inner surface of the second outer disc and the inner surface of the second inner disc, and first and second support means provided substantially in parallel with each other at sides of the first and second inner discs with the interposition of the first and second inner discs in such a manner that one ends are disposed between the first outer disc and the first inner disc and the other ends are disposed between the second outer disc and the second inner disc; and the first support means supports two of the four first pivot shafts and two of the four second pivot shafts for rocking movement and axial displacement, and the second support means supports the other two of the four first pivot shafts and the other two of the four second pivot shafts for rocking movement and axial displacement.
Particularly, the toroidal type continuously variable transmission according to the present invention is characterized in that members constituting the support means or the first and second support means are directly supported by and secured to an inner surface of the casing.
According to the toroidal type continuously variable transmission of the present invention having the above-mentioned arrangements, a rotational force is transmitted between the input disc or the first and second outer discs and the output disc or the first and second inner discs, and, a speed change ratio between the input disc or the first and second outer discs and the output disc or the first and second inner discs can be changed in the same manner as the conventional toroidal type continuously variable transmissions.
Particularly, in the toroidal type continuously variable transmission of the present invention, since the members constituting the support means or the first and second support means are directly supported by and secured to the inner surface of the casing, the number of parts is reduced to facilitate manufacture, control and assembling of the parts, and a height of the toroidal type continuously variable transmission is decreased to make the transmission compact and light-weighted while ensuring the endurance.
In a toroidal type continuously variable transmission according to another aspect of the present invention, yokes having ends for supporting the pivot shafts provided on the ends of the plurality of trunnions forming a part of the support means are directly supported by and secured to the inner surface of the casing. Further, it is designed so that the pivot shafts can be displaced axially, by splines, with respect to the ends of the yokes, and needle bearings for rockably supporting the pivot shafts are provided within the inside of the splines.
In a toroidal type continuously variable transmission according to a further aspect of the present invention, yokes having four corners for supporting the pivot shafts provided on the ends of the plurality of trunnions forming a part of the first and second support means are directly supported by and secured to the inner surface of the casing. Further, it is designed so that the pivot shafts can be displaced axially, by splines, with respect to the four corners of the yokes, and needle bearings for rockably supporting the pivot shafts are provided within the inside of the splines.
In this way, in the toroidal type continuously variable transmission of the present invention, since the yokes constituting the support means or the first and second support means are directly supported by and secured to the inner surface of the casing, the number of parts is reduced to facilitate manufacture, control and assembling of the parts, and a height of the toroidal type continuously variable transmission is decreased to make the transmission compact and light-weighted while ensuring the endurance.
Furthermore, since the yokes support the pivot shafts provided on the ends of the plurality of trunnions, all or part of forces acting on the plurality of trunnions can be canceled in the yokes. Thus, since a great load does not act on the casing supporting the yokes, it is not required that the wall thickness of the casing be increased in order to prevent displacement of the support portions for the pivot shafts and reduction in endurance of the casing.
In addition, since the splines and the needle bearings are provided between the pivot shafts and the yokes, the displacement of the trunnions with respect to the yokes can be effected smoothly and correctly.
It may be designed so that the splines are ball splines, and outer peripheral surfaces of outer races formed in inner peripheral surfaces of ball spline grooves constituting the ball splines are formed as semi-spherical convex surfaces, and the convex surfaces are rockably receiving in circular holes formed in the yokes.
Incidentally, a gear transmitting mechanism may be provided between the plurality of trunnions to synchronize the inclination movements of the trunnions.
A toroidal type continuously variable transmission according to a further aspect of the present invention comprises a casing, input and output discs supported within the casing in coaxial with each other and capable of being rotated independently so that inner surfaces of the discs are opposed to each other, four or more and the even number of pivot shafts disposed in coaxial with or parallel with each other between the input disc and the output disc at twisted positions where the pivot shafts do not intersect with a central axis of the discs but extend toward directions perpendicular to the central axis, a plurality of trunnions rockable around the pivot shafts, displacement shafts protruded from inner surfaces of the trunnions, a plurality of power rollers rotatably supported around the displacement shafts and interposed between an inner surface of the input disc and an inner surface of the output disc, and a plurality of actuators having the same number as that of the trunnions and adapted to displace the trunnions along axial directions of the pivot shafts.
A toroidal type continuously variable transmission according to a still further aspect to the present invention comprises a casing, first and second outer discs supported within the casing in coaxial with each other and capable of being rotated synchronously so that inner surfaces of the discs are opposed to each other, a first inner disc supported in coaxial with the first and second outer discs and capable of being rotated independently from the first and second outer discs and having an inner surface opposed to the inner surface of the first outer disc, a second inner disc supported in coaxial with the first inner disc and capable of being rotated synchronously with the first inner disc and having an inner surface opposed to the inner surface of the second outer disc, four or more and the even number of first pivot shafts disposed in coaxial with or parallel with each other between the first outer disc and the first inner disc at twisted positions where the pivot shafts do not intersect with a central axis of these discs but extend toward directions perpendicular to the central axis, a plurality of first trunnions rockable around the first pivot shafts, first displacement shafts protruded from inner surfaces of the first trunnions, a plurality of first power rollers rotatably supported around the first displacement shafts and interposed between the inner surface of the first outer disc and the inner surface of the first inner disc, four or more and the even number of second pivot shafts disposed in coaxial with or parallel with each other between the second outer disc and the second inner disc at twisted positions where the pivot shafts do not intersect with a central axis of these discs but extend toward directions perpendicular to the central axis, a plurality of second trunnions rockable around the second pivot shafts, second displacement shafts protruded from inner surfaces of the second trunnions, a plurality of second power rollers rotatably supported around the second displacement shafts and interposed between the inner surface of the second outer disc and the inner surface of the second inner disc, and a plurality of actuators having the same number as that of the trunnions and adapted to displace the trunnions along axial directions of the pivot shafts.
Particularly, in the toroidal type continuously variable transmission of the present invention, there is provided a synchronizing mechanism for mechanically synchronizing the displacement movements of the trunnions along the axial directions of the pivot shafts effected by the actuators.
For example, such a synchronizing mechanism may comprise receiving pieces having proximal ends secured to the ends of the trunnions and secured to tip ends of drive rods capable of being displaced axially by the actuators to displace the trunnions along the axial directions of the pivot shafts, and rocking arms having ends engaged by the receiving pieces to be merely rocked and central portions pivotally supported by a second pivot shaft (fixed portion) arranged in parallel with a rotational center line of the discs.
As is in conventional toroidal type continuously variable transmissions, in the toroidal type continuously variable transmission of the present invention having the above-mentioned arrangement, the rotational force is transmitted between the input disc and the output disc or between the first and second outer discs and the first and second inner discs, and, further, by changing the inclination angles of the trunnions, the rotational speed ratio between the discs is changed.
Particularly, in the toroidal type continuously variable transmission of the present invention, since the displacement movements of the trunnions along the axial directions of the pivot shafts effected by the actuators are mechanically synchronized, even when a quick speed change operation is performed, the inclination angles of the trunnions can be coincided with each other exactly.
The other objects and features of the present invention will be apparent from the following detailed explanation of the invention referring to the accompanying drawings.